Greige Stephanie, Abdallah Mohamad, Webster Christina F, Harb Moustapha, Beyenal Haluk, Wazne Mahmoud
Department of Civil and Environmental Engineering, Lebanese American University, 309 Bassil Building, Byblos, Lebanon.
The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA.
Enzyme Microb Technol. 2025 Aug;188:110650. doi: 10.1016/j.enzmictec.2025.110650. Epub 2025 Apr 3.
This study was conducted to delineate microbial community development and composition on both working and counter electrodes in single-chamber microbial electrolysis cells (MECs) using synthetic wastewater. Two separate bioelectrochemical reactors were inoculated with anaerobic sludge. The first was operated at an anodic potential poised at + 0.4 V and the second one at a cathodic potential poised at -0.7 V, both vs. an Ag/AgCl reference electrode. The performance of the MECs, including current generation, bioelectrochemical activity of the biofilms on both the working and counter electrodes, and chemical oxygen demand (COD) depletion were monitored over the last 45 days of operation. Scanning electron microscopy (SEM) and 16S rRNA gene sequencing were performed to delineate the development and morphology of the microbial communities on both the working and the counter electrodes. The current generated at the anodic working electrode provided evidence of the growth of anode-respiring exoelectrogens (Clostridium sensu stricto). Similarly, the Faradaic current data at the cathodic working electrode confirmed the formation of an electroactive biofilm dominated by acetoclastic and hydrogenotrophic methanogens (Methanothrix and Methanobacterium). Microbial communities on the counter electrodes were found to be richer but less diverse compared to those on the working electrodes. These communities were likely influenced by the fluctuating potentials at the counter electrodes. SEM observations were consistent with the microbial analysis. These findings demonstrate the ability of a mixed inoculum to shift towards anode-reducing and cathode methanogenic communities using a complex substrate on a constant working electrode and varying counter electrode potentials.
本研究旨在利用合成废水描绘单室微生物电解池（MEC）中工作电极和对电极上微生物群落的发展及组成。两个独立的生物电化学反应器接种了厌氧污泥。第一个反应器在阳极电位为 +0.4 V（相对于 Ag/AgCl 参比电极）下运行，第二个在阴极电位为 -0.7 V（相对于 Ag/AgCl 参比电极）下运行。在运行的最后 45 天内监测了 MEC 的性能，包括电流产生、工作电极和对电极上生物膜的生物电化学活性以及化学需氧量（COD）的消耗。进行了扫描电子显微镜（SEM）和 16S rRNA 基因测序，以描绘工作电极和对电极上微生物群落的发展及形态。阳极工作电极产生的电流证明了阳极呼吸性外生电子菌（严格意义上的梭菌属）的生长。同样，阴极工作电极的法拉第电流数据证实了由乙酸裂解型和氢营养型产甲烷菌（甲烷丝菌属和甲烷杆菌属）主导的电活性生物膜的形成。与工作电极上的微生物群落相比，发现对电极上的微生物群落更丰富但多样性更低。这些群落可能受到对电极上波动电位的影响。SEM 观察结果与微生物分析一致。这些发现表明，使用混合接种物在恒定的工作电极和变化的对电极电位下，利用复杂底物能够转向阳极还原型和阴极产甲烷型群落。
